Me and my friend have been writing a multiplayer game (similar to MOAGG, but focused on multiplayer). I had finally written a fair portion of the networking code. I tested it running two copies on my computer. It worked, somewhat slowly. Then, I gave my friend an updated copy. He ran it. His client connected to the server, recieved the map to load, and then, while trying to send its coordinates got "Error 10,004", in a simple socket.sendto statement. This is a Winsock blocking error. If it makes any difference, part of the socket code is within a thread, while part of it is not. In any case, I am completely out of ideas. Any help would be greatly appreciated.